Hydration of Oligosaccharides

Abstract

The spin-lattice relaxation times, T1, of H217O have been measured for aqueous solutions of 2 di-, 2 trisaccharides, α-, and γ-c clodextrins as a function of the concentration at 25°C. The dynamic hydration numbers, nDHN, for 17 sugars including monosaccharides were expressed by the linear relation of the mean number of the equatorial OH groups. The second virial coefficients showed a good correlation with nDHN. Though the rotational correlation times, τch, of water molecules in the cosphere of sugar molecules increased with increasing the number of equatorial OH groups for monosaccharides, those for trisaccharides and cyclodextrins showed almost constant values. The relation between the values of the limiting diffusion coefficients and nDHN for sugars was found to be expressed by two lines with a large negative slope for mono- and di- saccharides, and a small negative slope for trisaccharides and cyclodextrins.

Effect of sugars on the thermal and rheological properties of sago starch

“…A good correlation has been reported between DHN and the number of equatorial hydroxyl groups in the sugar molecules. 32 The T gel was found to increase approximately linearly at all sugar concentrations with the DHN of the various sugars apart from ribose, which had little effect even at 50% concentration. A good linear relationship was shown between ⌬H and DHN for the starch dispersions in the presence of all the sugars at a concentration of 50%.…”

“…Figures 5a and 5b show a plot of T gel and ⌬H, respectively, for 10% starch dispersions vs the dynamic hydration number (DHN) for the various sugars obtained from Uedaira et al 32 The DHN 32 is defined as…”

Reorientational dynamics, hydrogen bonding and hydrophilicity of X-ray contrast agents in solution

“…They were obtained after optimization of the molecular structures and were found to be in a The densities and viscosities for the solutions of the contrast agents 1 to 5 in dimethylsulfoxide (DMSO), water and methanol were determined at a temperature of 310 K, and the results are compiled in Table 1. The spin-lattice relaxation times T 1 for the 13 C nuclei with directly bonded protons were measured at 310 K for the contrast agents 1 to 5 in their different solutions and are listed in Table 2. The relaxation times for carbon atoms without directly bonded protons are significantly longer and are not considered in this study any further.…”

“…Some of the peaks could not be assigned to a specific carbon atom in the molecule or could not be resolved in the spectrum; their relaxation times are combined in Table 2. Furthermore, some 13 C nuclei give more than one signal, depending on the solvent, because they form isomers in which the corresponding nuclei show different chemical shifts.…”

“…The analysis of the relaxation data is achieved under the assumption that the reorientational motion is in the extreme narrowing regime and that all 13 C nuclei with directly bonded protons relax via the dipolar mechanism. For this situation the observed spin-lattice relaxation time T 1 is equal to the dipolar spin-lattice relaxation time T …”